I use a combination of pomodoro sessions and 20/20/20 rule. So at least twice an hour I'll get up and stretch my legs and get the blood flowing and rest my eyes

I use a combination of pomodoro sessions and 20/20/20 rule. So at least twice an hour I'll get up and stretch my legs and get the blood flowing and rest my eyes while I look out the window. It's too easy to get in the zone and not move at all from your chair with your eyes trained to the same distance on the screen.